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. iea-nuracrunnor umnrnnmnnnnn cnnnunorn- Tacit whom it may concern:

"Be it known that I, HENRY Drums, of

Basel, Switzerland, a citizen 'of" the Rethis designation, films, or other articlesof' public of Switzerland, have invented certaiii new and useful Improvements "in the Manufacture of Uninflammable Celluloid, of which the following is a specification.

. This invention has reference to the manu facture of uninfiammable celluloid having,

a basis of acetate of cellulose, including in.

manufacture composed of. such celluloid.

Tn the specification of 'my United States Patent 1,217,722 and Reissued Patent No.

14,338, and of my applications for United State Patents Serial'No. 25,820, filed May, 4:,

i 1915, Serial-No. 103,862, filed June 15, 1916 Serial No. 52,297, 'fil d September .23, 1915,

, These processes low of regulat' cosity as desire by makinggra ations of and Serial No.- 73,459 filed January 21st, 1916, T have described processesfor the manufacture of acetate of cellulose having in their clear solutionafor example. by way of comparison, in acetone, very high visfiosity.

5t evischanges during the production of the acetate;

Thus viscosities can be produced varying from about 12 to 20, 30, 10, 50, 100 and even I 150 and more (as measuredby the Us'twald vis osimeter as used for example in the specitica ion of the British Aeronautical lnspetion Directorate), whereas with the other known processes for the manufacture of eel-r lulose acetate, it is not possible to gradate to these viscosities or even to attain a viscosity ofmore than about This is due to the" fact thatin order to obtain acertain viscosity it .is necessary to pass through the direct acetylation processes as described inthe specifications above indicated which produce, as an intermediate material, by direct acetylation with the acetylating mixture, ace:

,- tate of cellulose, which, after acetylation and precipitation when the clear solution is obtained, represent 1 products insoluble in chloroform, which may be soluble in addition. of more or less alcohol, or other products which do not dissolve even on addition of alcohol. i e

But, be it understood, according to the gradations orsmall changes ofprocedure f that are applied for these products in a second process which has nothing to do with acetylatlon, one can (according to the exact r fiqa e letters P t Patented Dec. 23, 1919..

Application filed February 15, 1918., semi m). 2173378.,J

It is moreover a recognized fact (similarly to what is the casewith nitrocellulose) that the more viscous acetates of cellulose are, the i better is their quality. A product of low viscosity gives for example celluloid or films which. -are'brittle as compared with those made with a more viscous acetate of cellu- .lose, that is to say the strength of 'a cellulose acetate of low viscosity is much less than that of an acetate of high viscosity, and one might almostsay, up to a certain point, that the strength of the finished products. in

creases with the increase of viscosity.

This is understandable from the fact that themore viscous the product is, the more-is the cellulose it contains still intactand not depolymerized, as in a product "of more or less low viscosity;

' l[ have found, both for the manufacture of films and for the manufacture of celluloid that in proportion to increase of their viscosity the acetates of cellulose will bear 4 greater and greater quantities of softening or plasticizing agents having high boiling points, without the finished products become ing too supple or becoming oily from the excess of the softening substances. These cel- ;-lulose acetate products having 'a-larger con tent of softening agents acquire WmOTQ' strength from every point of view.

Thus for example, "and to explain the process, it has been/found that to make nonmflammable celluloid, using triacetin as softening agent, 'it is hardly possible, for an acetate of cellulose having a viscosity of about *8 to 12, to employ more than 10 to per cent. of 'triacetin calculated on the weight of cellulose acetate employed havin% the said viscosity. Tf on the contrary vone employs an acetate of cellulose having a viscosity of to one can readily incorporate with it 40 and even er cent. of triacetin calculated on the weig t of the cellulose acetate having a viscosity of about 35 to 4:5, and without the finished product becoming oily or too soft,

' Evident y if cellulosetacetates are em- I' ployed having still greater viscosities, up to 100 or 150, the quantity of triacetin can be ous effects from'the optical. or physical point of view, such as metallic powders, luminous Ior hosphoresc'nt substances and sofforth. he importance of the resultsobtainable by the present invention can be appreciated if they are compared with those obtainable 'up to the present in the manufacture of Celluloid and ,films with nitrocellulose as a base. 5 If, for example, one takes an ordinary nitro-cellulose celluloid,.' (recognized asthe t best from all points of view), say a transparent celluloid, and isolates the nitrocllu-y lose therefr0m 1n an appropriate way, its

comparativevisco'sity, ascertained according to the same methods as for acetateof cellu-- scribed my name.

lose, is found to be about 45. Likewise for films, it is; found that the viscosity of the isolated" nitrocellulose is approximately 55.

v Thusbyamy rocesses above referred to it is easy to attam. with acetate of cellulose,

the same viscosities as for thebest celluloid or the best films, or the best nitrocellulose contained therein heretofore known, in other words, one can obtain at least the same strength from all. oints of View as for inflammable celluloid though this has been thought to be impossible. Not only is this "result attained, but it is greatly exceeded with acetates of cellulose, manufactured according to my said processes, as wit l 1 th ese one-,cau attain much.v higher vlscoslt es, gomg to 100 and even 150 and more, while obtainingjproducts which give in acetone, solution, for exam le of a concentration of 20%, which SOlIltlOIlS. are as 0 car as water. I Y

hat I claim and desire to secure by Letters Patent is: Y 1 4 In. the manufacture. of non-inflammable celluloid masses, the step of adding a plasticizing. agent to cellulose acetate, the

amount of s'uch plasticizing agent being the greater, the greater the viscosity of the cellu:

lose acetate used. 4

In testimony whereof I have hereunto sub HENRY DREYFUS 

